While the metrocells that AT&T is currently deploying support UMTS and HSPA+, the carrier plans to push forward with more advanced technology in the future. Later this year the carrier expects to deploy units that will also support Wi-Fi and LTE, but it has not released the name of the vendor yet.
Jim Parker, AT&T spokesman, told AGL Small Cell Link, “Metrocells are largely in their infancy. They support a single technology, a single frequency band and a single sector. It is extremely limited.”
AT&T requested a neutral host metrocell last summer from the OEMs through the Metrocell Forum, which created a requirements document and distributed it around the world. “We expect metrocells to evolve into a neutral hosting ability, but not for a few years,” Parker said.
The carrier is in the second year of its three-year Project Velocity IP, which will deploy 40,000 metrocells.
AT&T is deploying metrocells through three separate divisions, the Antenna Solutions Group, which targets large public venues, the Advanced Enterprise Mobility Solutions Group, which targets enterprises, and local RAN organizations, which are deploying them outdoors.
Expansion of the Addressable In-building Wireless Markets
AT&T is seeing significant growth in metrocell deployments in retail outlets, such as Best Buy and Walmart, because of the large number of customers, but also because they are retail outlets for the carrier’s phones. Metrocells can be economically deployed in places where a DAS network would be too expensive.
“The total number of addressable markets for wireless in-building systems has now significantly expanded with the advent of metrocells,” he said. “Now with metrocells at a much lower cost, we are able to go after markets that were previously unattainable, like multiple-dwelling units, retail and smaller hotel chains. We will even drop metrocells into the basement of a building that otherwise has good in-building coverage. In the past we would simply walk away from those opportunities.”
The carrier has negotiated master lease agreements with several nationwide chains of hotels and retail stores. Big box chain stores, with cinder block walls and metal roofs don’t always have the best macrocell penetration. An in-building metrocell helps facilitate the salesperson’s ability to activate the handset, according to Parker.
The decision to deploy metrocells versus DAS is also guided by capacity needs. Current metrocell technologies support up to 32 users. Compare that to a DAS. The DAS antenna can support multiple wireless operators, multiple wireless technologies, multiple frequency allocations, and the system can be expanded through sectorization.
Don’t expect to see a lot of metrocells in stadiums where capacity is king. Metrocells can be used where capacity needs are not as great, such as Marriott Courtyards.
“We are deploying metrocells in corporate America where the employees are encouraged to bring their own devices, but they don’t have adequate coverage,” Parker said.
Project Velocity IP, which includes macrocells, DAS and metrocells, had its first metrocells field application in the fourth quarter 2012, with wide-area deployments commencing the first quarter of last year. By 2015, metrocells will be the dominant technology of choice used in AT&T’s densification program, according to Parker.
“We are very much in the early stages of deployment and currently utilize specially trained personnel to deploy the metrocells, but due to their plug-and-play architecture, simple IP-connectivity and self-organizing architecture, we envision a day when we will be able to simply ship them to our enterprise customers and have their IT technicians deploy them,” Parker said.
The RF output of each metrocell varies from 39 milliwatts to 250 milliwatts, which is comparable to the power output of other indoor wireless solutions. The metrocell has a Fast Ethernet interface, which can use the building’s existing Internet access for backhaul and can be either shared or dedicated. The self-configuring architecture reduces the time and cost of installation.
Each metrocell can support 16 or 32 devices and can support simultaneous voice and high-speed data sessions. Each metrocell covers from 7,000 to 15,000 square feet depending on building layout and construction. Multiple metrocells can be deployed within a facility, allowing for seamless call handoff within the premises.
Each metrocell has a Fast Ethernet interface and can use the building’s existing Internet infrastructure, which offers less cost, simplified site acquisition and faster deployment. However, the quality and performance of the system is dependent upon the customer’s infrastructure, routers, switches and the cables that are maintained by the customer. The operator has restricted visibility into the network, making it more difficult to manage and maintain.
A metrocell can also be deployed with a dedicated network and backhaul, which provides additional network control for the operator, more network visibility and the ability to maintain the system end to end. The disadvantages of this approach are: more site acquisition requirements, running cable to each metrocell, increased capex and opex, and longer deployment time. More control over a network is always preferred by the carrier.
“We have been deploying our own LAN infrastructure to be able to manage and monitor end-to-end performance,” Parker said.
Metrocells Pass the Test
In the first field applications that took place in 2012, AT&T wanted to evaluate the performance of metrocells across a wide range of environments, including an outdoor residential area, an office campus and an urban high-rise in New York City.
For the outdoor environment, AT&T deployed 14 metrocells in the residential area of Crystal Lake Park, Mo., a small town located west of St. Louis. The system resolved spotty coverage caused by hilly topography. After deploying the metrocells, the macrocell performance improved with a 40 percent reduction in dropped calls.
To test the technology in the office campus environment, AT&T deployed 12 metrocells in an office building in Waukesha, Wis. “We realized a 15 percent increase in network traffic and a reduction in the call drop rates,” Parker said. “With ubiquitous wireless coverage throughout the facility, we have seen a significant increase in data traffic with more than 50,000 data sessions per day.”
AT&T deployed 20 metrocells for multiple enterprise customers in New York City. In order to reduce the amount of time to deploy the system, the carrier used the customers’ existing Internet wiring or a shared network to backhaul the metrocells.
Ballyhooed by some, feared by others (DAS providers) and a source of confusion for most, small cells continue to move from concept to reality, allowing carriers to fill in dead spots, beef up congested areas and provide coverage for enterprises.
During the second half of 2013, Verizon Wireless will begin deploying small cells in its LTE network, which totals 497 markets, using access points from network vendors Alcatel-Lucent and Ericsson.
“As part of an overall 4G LTE network, [small cells] help deliver the quality, reliability, footprint and capacity to accommodate new applications, the burgeoning use of video and the popularity of smartphones and tablets with larger screens and sharper images,” according to a Verizon Wireless blog.
More than 200 LTE small cells will be deployed in the next six months to enhance localized capacity and coverage in business districts and shopping malls, wherever there is concentrated traffic. Because they are only the size of a mini refrigerator, small cells can be deployed on lampposts, utility poles and building walls.
“Like macro cells, they must be connected to the core wireless network and may pose operational challenges ranging from site acquisition and leasing to regulation and permitting by local authorities. While not a panacea, they are a valuable addition to a 4G LTE network, part of a balanced network strategy,” according to a Verizon press release.
Ericsson will be providing its micro remote radio unit small cells (RRUS) for Verizon’s LTE network, which can be easily integrated into the overall network because it works with any baseband unit as part of the RBS 6000 product line. It is the first commercial deployment of Ericsson’s micro RRUS.
Later this year, Ericsson will also provide Verizon with the micro RBS 6501, which is a multi-standard base station supporting 3GPP 37.104 and provides local-area and medium-range coverage in a heterogeneous network environment. The micro RBS delivers high-capacity coverage in a small form factor.
Small Cells Already Seeing Action for AT&T
AT&T has been rolling out HSPA+ small cells since the beginning of this year as part of its Velocity IP program and is planning to deploy a multi-technology (UMTS, LTE and Wi-Fi) version of the small cell in 2014. Jim Parker, AT&T spokesman, told DAS Bulletin that small cells would complement DAS deployments.
“It is interesting to see where small cells play,” Parker said. “In vertical markets where they demand neutral host access points, such as airports, shopping centers, major hotels, that is where DAS still has a play. This is not the death knell for DAS.”
Small cells will be deployed in distinct verticals where there is an unmet need and DAS is not a cost-effective solution, such as the enterprise, where it is easy to install the access points above ceilings and to use the company’s backbone to backhaul the signal, Parker said.
“We are really going after the enterprise market and other public venues, such as smaller hotels,” he said.
AT&T is deploying small cells outdoors where they have a need for additional capacity. To gain real time on where the network is suffering from congestion, the carrier uses feedback directly from its phones, which record the location of a dropped or blocked call and then transmit it back to the carrier.
“I can pull up a map of the United States on a computer that shows all the cell towers and, in real time, check to see which towers are under a heavy load,” he said. “Using these diagnostics, we are able to develop a strategy for small cell deployment.”